Blog Alien Eyes features an obvious (but handy) tip for quickly converting the time on a 24 hour clock. Subtract 10 then 2 to get the 12 hour clock time:

13 — 3 - 2 = 1pm

14 — 4 - 2 = 2pm

15 — 5 - 2 = 3pm

16 — 6 - 2 = 4pm

17 — 7 - 2 = 5pm

18 — 8 - 2 = 6pm

19 — 9 - 2 = 7pm

20 — 10-2 = 8pm

21 — 11-2 = 9pm

22 — 12-2 = 10pm

23 — 13-2 = 11pm

00 — If ya can't work that one out, don't bother with 24hrs

Having switched my watch to 24 hours a couple of years ago, I don't have to do the math anymore (you just get used to it.) But for occasional 24ers, this is a good method. Thanks, Sujith!— Gina Trapani